Photo Credit: James Grenz

Hilo

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 79 to 84 near the shore to 64 to 72 at 4000 feet. Northeast winds around 10 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows 63 to 71 near the shore to around 56 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 20 percent.

Saturday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 79 to 84 near the shore to 64 to 72 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Kona

Today: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 81 to 88 near the shore to around 71 near 5000 feet. Light winds. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows around 72 near the shore to 48 to 54 near 5000 feet. Light winds. Chance of rain 50 percent.

Saturday: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 81 to 89 near the shore to around 72 near 5000 feet. East winds up to 10 mph shifting to the west around 10 mph in the afternoon. Chance of rain 50 percent.

Waimea

Today: Partly sunny with scattered showers. Highs 67 to 88. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 62 to 70 near the shore to 53 to 62 near 3000 feet. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 50 percent.

Saturday: Mostly sunny with isolated showers early in the morning, then mostly cloudy with scattered showers in the late morning and afternoon. Highs 67 to 89. East winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 50 percent.

Kohala

Today: Partly sunny with scattered showers. Highs 67 to 88. Northeast winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then partly cloudy with isolated showers after midnight. Lows 62 to 70 near the shore to 53 to 62 near 3000 feet. East winds 10 to 15 mph decreasing to up to 15 mph after midnight. Chance of rain 50 percent.

Saturday: Mostly sunny with isolated showers early in the morning, then mostly cloudy with scattered showers in the late morning and afternoon. Highs 67 to 89. East winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 50 percent.

South Big Island

Today: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 82 to 87 near the shore to around 68 near 5000 feet. East winds up to 15 mph shifting to the south in the afternoon. Chance of rain 50 percent.

Tonight: Mostly cloudy with scattered showers in the evening, then mostly clear after midnight. Lows around 72 near the shore to around 51 near 5000 feet. Southeast winds up to 15 mph shifting to the north after midnight. Chance of rain 50 percent.

Saturday: Sunny early in the morning, then partly sunny with scattered showers in the late morning and afternoon. Highs 82 to 88 near the shore to around 69 near 5000 feet. Northeast winds up to 15 mph shifting to the south in the afternoon. Chance of rain 50 percent.

Puna

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 79 to 84 near the shore to 64 to 72 at 4000 feet. Northeast winds around 10 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with isolated showers. Lows 63 to 71 near the shore to around 56 at 4000 feet. Northwest winds up to 10 mph. Chance of rain 20 percent.

Saturday: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 79 to 84 near the shore to 64 to 72 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 20 percent.

Waikoloa

Today: Mostly sunny with isolated showers in the morning, then mostly cloudy with numerous showers in the afternoon. Highs 81 to 90 near the shore to 67 to 75 above 4000 feet. Light winds becoming northwest up to 10 mph in the afternoon. Chance of rain 60 percent.

Tonight: Mostly cloudy with numerous showers in the evening, then mostly clear after midnight. Lows around 73 near the shore to 49 to 56 above 4000 feet. Light winds. Chance of rain 60 percent.

Saturday: Sunny early in the morning, then mostly cloudy with numerous showers in the late morning and afternoon. Highs 81 to 91 near the shore to 68 to 76 above 4000 feet. Southeast winds up to 10 mph shifting to the northwest around 10 mph in the afternoon. Chance of rain 60 percent.

Detailed Forecast

Synopsis

A cold front approaching the Hawaiian Islands from the far north will weaken the high pressure ridge over the region and decrease trade winds over the state through Sunday. Local scale sea breezes will develop over each island as these large scale winds diminish. The latest guidance continues to show this weakening front slowing down as it approaches the islands spreading cloudy skies and showers across Kauai, Niihau, Oahu and Molokai from Sunday to Monday as it stalls out near Molokai by Monday afternoon. Light to moderate trade winds will then continue through much of next week with continued land and sea breeze winds over terrain sheltered leeward areas with brief showers possible.

Discussion

Clouds associated with a weak low level trough continue to drift westward through the islands this morning. These clouds and showers will diminish in coverage a few hours after sunrise. A cold front roughly 500 miles north of Kauai this morning will slowly weaken and approach the islands over the next few days. This frontal boundary will likely produce cloudy skies and showers over the islands of Kauai, Niihau, Oahu and Molokai on Sunday and Monday.
The subtropical ridge north of the islands will weaken over the next few days in response to a cold front approaching the islands from the north. Large scale trade winds will weaken allowing island heating to drive local scale sea breezes each day over all islands through Sunday. The latest weather guidance continues to show the front drifting into Kauai, Niihau and Oahu on Sunday and then reaching Molokai by Monday morning. This system will spread cloudy skies and showers across these central and northwestern islands, especially over the windward and mountain slopes. The highest rainfall amounts are forecast over windward and mountain areas as trade winds return with lingering instability after the front passes through each island.
Northeast trade winds will strengthen north of the frontal boundary as it passes through each island. This front will fade away from Monday to Tuesday with moderate trade winds spreading out to all islands along with passing windward shower activity. Overall trade winds will likely remain in the light to moderate levels from Tuesday into the end of next week with afternoon sea breezes and overnight land breezes expected mainly over terrain sheltered leeward areas.
Some uncertainty remains in how far south this front will travel into the islands before it fades away. The American (GFS) model keeps the frontal boundary intact until the front reaches Maui on Monday. While the European (ECMWF) model is also showing a similar forecast, which is a change from the previous model run. We have blended the older model solutions with the latest runs for clouds, showers and rainfall to minimize errors of any individual model solution. However, Maui may yet see increasing shower activity on Monday if the latest GFS and ECMWF models hold in their latest prediction on how far south this cold front can travel before stalling out. Stay tuned for updates as this part of our forecast may change for the Monday and Tuesday time periods.

Aviation

Moderate trades will deliver clouds and showers mainly to windward zones for the remainder of the predawn hours before an influx of drier air brings marked improvement during mid-morning and lasting for the remainder of the day. In the meantime, AIRMET Sierra for mountain obscuration for portions of Windward Big Island and Kauai will remain in effect.

Marine

Light to moderate trades will hold in place through Saturday as a front approaches from the north. The front will sag southward into the islands late Saturday night and Sunday, bringing a return of moderate to fresh trade winds. The front will stall out and dissipate over state early next week, with moderate trades generally prevailing through late next week.
A small north-northwest swell will build today, peak tonight and Saturday, then lower Sunday into early next week. A slightly larger north swell with a shorter period will arrive late today and tonight then peak over the weekend. A moderate size longer period north-northeast swell should arrive late Sunday or Sunday night. This swell may peak at low end advisory levels along north facing shores Monday, then slowly decline through late next week. Another small medium period northwest swell appears to move through the islands Monday through the middle of next week as well.
Surf will remain small along south facing shores over the next few days with mainly background energy from the south and southeast. Another small, more noticeable long-period south swell is expected to fill in Sunday into Monday with a slow and gradual decline through late next week.
East facing shores will remain small and well below normal during the next 7 days due to a lack of strong trade winds over and upstream of the islands.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov